This invention is in the field of intraocular lenses for correction of aphakia by implantation in the posterior chamber of the human eye. More specifically, the present invention is directed to an intraocular lens for self-centered non-sutured, positioning in the lens capsule of the human eye following extracapsular removal of the natural lens therefrom.
It has long been recognized and accepted that an intraocular lens implanted in the human eye following cataract surgery will provide substantially better vision than is possible with the use of either of the available alternatives of contact lens or spectacles. However, while the first intraocular lens implantations were begun by Dr. Harold Ridley in 1949, who implanted a plastic lens in the posterior chamber following an extracapsular cataract extraction, there were a large percentage of complications such as iritis, pupillary occlusion, dislocation of the lens and the like which prevented general acceptance of intraocular lens implantation.
A wide variety of lens constructions and surgical techniques subsequently evolved as the result of efforts to overcome the problems of the original Ridley lens. Generally speaking, the majority of subsequent efforts were directed toward the provision of a lens for implantation in the anterior chamber of the eye due primarily to the easier accessibility of the anterior chamber and the fact that the lens could be easily positioned by the surgeon in a manner not possible with a posterior chamber mounted lens. Earlier anterior chamber lenses were supported by contact with the anterior chamber angle and also frequently contacted the cornea. Entirely satisfactory results were not always achieved with the more frequent complications including corneal dystrophy resultant from endothelial contact, corneal edema, and inherent optical inadequacy in not providing full binocular vision and optical malfunction due to mispositioning. Subsequent anterior chamber positioning was achieved by fixation to the iris with the most successful lens of this general type being that of Binkhorst employing rigid posterior chamber loops extending through the pupil to the anterior chamber positioned lens. Unfortunately, erosion of the iris sometimes results with these and other iris contacting or attached lenses.
Other previously proposed lens attachment and mounting means have included rigid loops, arms, plates, legs and the like which have been held in place by sutures, such as exemplified by the rigid loops 12 and 13 in Jensen U.S. Pat. No. 4,110,848 and by rigid plates 12 and 13 of Kelman U.S. Pat. No. 4,092,743, with the sutures extending through the iris. Prongs 13 etc. extending through the iris are disclosed in the Flom U.S. Pat. No. 3,866,249. Jensen Pat. No. 3,994,027 and Peyman U.S. Pat. No. 4,073,015 both disclose rigid support loops engaging the anterior capsule wall.
Iris-engaging clip support for a posterior lens is shown in Richards et al U.S. Pat. No. 4,014,049. In many instances, the lens body itself also contacts the iris and in the case of the majority of posterior chamber implants, the lens body contacts or exerts pressure on the ciliary body in the manner of the original Ridley lens and as more recently exemplified in the aforementioned Richards et al patent and Potthast U.S. Pat. No. 3,913,148 so as to create the possibility of tissue necrosis.
Another recent posterior chamber lens is disclosed in Shearing U.S. Pat. No. 4,159,546 in which J-shaped elastic support members extend outwardly from opposite peripheral edges of the lens to engage the ciliary body, or possibly the lens capsule, to support the lens in position. Unfortunately, the J-shaped support members do not have substantial resistance to torsional twisting and flexing and it is consequently difficult to accurately and predictably position the lens and its support members in the posterior chamber.
For a more extensive treatment of prior known intraocular lenses, reference is also made to my prior publications Bridge Over Troubled Waters and Covered Bridge.
Notwithstanding the great strides made in lens implantation since the original Ridley activity as evidenced by the thousands of successful lens implantations, complications in individual cases continue to arise in a small percentage of the cases. In addition to the previously noted corneal and other problems, unsatisfactory results can arise from the lens becoming mispositioned for a variety of reasons such as erosion of the iris or the ciliary body portion of the eye with which the support and positioning elements are engaged. Improper sizing and excessive weight of the lens and support elements also causes subsequent mispositioning of the lens in some instances. It is consequently desirable to avoid the use of sutures and other similar connectors engaging viable portions of the eye and to minimize contact of the lens and its support means with the iris and ciliary body to the fullest extent possible.